The present invention is directed to a process for stabilizing asphalt compositions and to compositions for attaining the desired result.
Asphalt material is utilized in many applications including road formation, roofing compositions, roofing materials (shingles, felt etc.), waterproofing coatings and compositions, etc. The material is normally a product obtained as the bottoms from petroleum distillation directly or upon further processing of the bottom material, such as by steam distillation or the like. The initially obtained asphalt has flow characteristics which make it unsuitable for a number of applications. The raw asphalt normally has a low softening point (e.g. 120.degree. F.) which causes it to flow at relatively low temperatures and, therefore, is unsuitable in applications such as roofing material and the like. It is customary to treat the raw asphalt to increase its softening point. This is commonly done by blowing oxygen (or air) into molten asphalt to increase the asphaltenes in the composition and, thus, to raise its softening point to a desired range (e.g. 180.degree. -200.degree. F.). Such materials are known as blown asphalt or oxidized asphalt.
Asphalt compositions having elevated softening points are normally stored for several days as a liquid in commercial application. Storage is normally done at 300.degree.-500.degree. F. in order to provide a fluid composition which is easily handled and processed into final products. During storage at such elevated temperature, the asphalt material undergoes reversion, a reduction in its softening point. This poses the problem of having asphalt which is not of the quality desired (i.e. has too low a softening point) or requires excessive initial oxidation to produce a higher grade product with the intention of providing a controlled degree of degradation to achieve the asphalt of desired quality. The former condition is not commercially acceptable and the latter method is economically unacceptable and difficult to control.
Several methods have been suggested to control and stabilize asphaltic material including the addition of soaps to the composition. However, such materials are not compatible with asphalt and are not readily mixable to form a uniform composition which can sustain elevated temperatures over a sustained period.
It is highly desired to develop a method which will provide for a means of stabilizing asphaltic compositions from undergoing reversion of its softening point while being stored in a liquid state at elevated temperatures.